More than 200 chemicals – many found in urban air and everyday consumer products – cause breast cancer in animal tests, according to a compilation of scientific reports published Monday.

Writing in a publication of the American Cancer Society, researchers concluded that reducing exposure to the compounds could prevent many women from developing the disease. The research team from five institutions analyzed a growing body of evidence that linked environmental contaminants to breast cancer, the leading killer of U.S. women in their late 30s to early 50s.

Experts say that family history and genes are responsible for a small percentage of breast cancer cases but that environmental or lifestyle factors such as diet are probably involved in the vast majority.

“Overall, exposure to mammary gland carcinogens is widespread,” the researchers wrote in a special supplement to the journal Cancer. “These compounds are widely detected in human tissues and in environments, such as homes, where women spend time.”

The scientists said data were too incomplete to estimate how many breast cancer cases might be linked to chemical exposures.

But because the disease is so common and the chemicals so widespread, “the public health impacts of reducing exposures would be profound even if the true relative risks are modest,” they wrote. “If even a small percentage is due to preventable environmental factors, modifying these factors would spare thousands of women.”

The three reports and a commentary were compiled by researchers from the Silent Spring Institute, a women’s environmental health institute in Newton, Mass.; Harvard’s Medical School and School of Public Health in Boston; the Roswell Park Cancer Institute in Buffalo, N.Y.; and the Keck School of Medicine at the University of Southern California. Silent Spring Institute Executive Director Julia Brody led the team.

In response to the findings, Susan G. Komen for the Cure, a breast cancer prevention group that funded the work, pledged an additional $5 million for developing improved research tools to root out environmental causes.

Reviewing hundreds of existing studies and databases, the team produced what it called “the most comprehensive compilation to date of chemicals identified as mammary carcinogens.” No new chemical testing was conducted for the reports.

They named 216 chemicals that induce breast tumors in animals. Of those, people are highly exposed to 97, including industrial solvents, pesticides, dyes, gasoline and diesel exhaust compounds, cosmetics ingredients, hormones, pharmaceuticals, radiation and a chemical in chlorinated drinking water.

“Almost all of the chemicals were mutagenic, and most caused tumors in multiple organs and species; these characteristics are generally thought to indicate likely carcinogenicity in humans, even at lower exposure levels,” they reported.

For many compounds, the federal government has not used animal breast cancer data when conducting human risk assessments, which are the first step toward regulating chemicals, or in setting occupational standards to protect workers. Companies do not have to screen women who work with the chemicals for breast cancer.

Toxicologists say that other mammals, such as rats and mice, often develop the same tumors as humans do, and that animal tests are efficient means of testing the effects of chemicals. Environmental regulators, however, often want conclusive human data before taking action.